An individual making life-sustaining treatment decisions pursuant to the provisions of the Oklahoma Advance Directive Act for a declarant shall make such decisions based on the known intentions, personal views and best interests of the declarant. If evidence of the declarant's wishes is sufficient, those wishes shall control.
If there is not sufficient evidence of the wishes of the declarant, the decisions shall be based on the reasonable judgment of the individual so deciding about the values of the declarant and what the wishes of the declarant would be based upon those values.
Okla. Stat. tit. 63, § 3101.16